SCARLET FEVER

Scarlet fever results from infection (usually of the throat) with Sir. pyogenes. It occurs only if the streptococcus produces the specific toxin in the host and if the host is susceptible to that toxin. The typical rash (and perhaps some of the other signs) is produced by this toxin, which is, therefore, often referred to as the erythrogenic toxin. Since there may be wide differences both in the toxigenicity and in the host-susceptibility, there is great variation in the severity of the clinical syndrome. Many mild cases occur which are liable to be missed and spread the infection. People who have become immune to the toxin are not immune to streptococcal infection. When they are infected, a streptococcal tonsillitis may occur, and such persons, perhaps even more than carriers, play an important part in the spread of the disease and render control virtually impossible.
Although infection very commonly occurs through the medium of the " missed case ", the contamination of animate or inanimate materials by strepto­coccal discharges is also of importance. Infected milk is a common cause of epidemics. In hospital wards, the dust may contain streptococci, and measures to reduce dust form an important aspect of control. After recovery, cases of both scarlet fever and tonsillitis which have not been specifically treated may continue to carry streptococci in the throat or nose. Nurses (especially mid-wives), teachers and individuals associated with the supply of milk should be subjected to detailed bacteriological examination after recovery from the infection and before return to work.
Scarlet fever has a short incubation period—-from two to five days—and is a notifiable disease.
Prevention and Control.—The Dick Test and Immunization.—A skin test, analogous to the Schick test, can indicate the capacity of the individual to deal with the erythrogenic toxin. It now has no more than historic interest, for, of course, it gives no indication of the individual's susceptibility to streptococcal infection. Control, by means of penicillin, of all forms of attack by Sir. pyogenes, is so complete that it is undesirable to commend the further use of the test, or the need to invoke an antitoxic immunity', whether active (by the injection of increasing doses of toxin) or passive (by the use in therapy of a specific antitoxin).
Penicillin.—Systemic penicillin will clear streptococci from the throat and in ward outbreaks in hospital the spread of the organism is limited by this treatment. In such conditions, with the patient under control, administration of oral phenoxymethylpenicillin for seven days usually suffices to break the chain of infection. Tetracycline-resistant strains of Str. pyogenes have been isolated recently. The bacteriologist should therefore examine all strains to exclude bizarre examples of resistance.
Gmeral Measures.—The patient must be promptly and effectively isolated. Children who are contacts should be excluded from school for one week. When the patient is treated at home—as he should be—some local health authorities still insist on the remaining susceptible children of the household being kept away from school throughout the entire period of treatment—an action completely unjustifiable on our knowledge of the spread of the disease and the rapid reduction of infectivity obtained with penicillin treatment.
A quarantine period of at least one week must be strictly enforced in the case of'adult contacts whose occupation entails the handling of milk or other foods or close contact with children. Such persons can be rendered free from infection by giving penicillin in full therapeutic doses. Cultures of throat and nose one week later are almost invariably found to be negative.
If an epidemic of streptococcal infection is to be stamped out in a residential school or institution, a knowledge of the type of Str. pyogenes responsible is valuable, so that cases of hsemolytic streptococcal tonsillo-pharyngitis and carriers of the specific organism may be isolated. Bacteriological assistance is obviously very important.
Curative Treatment —Chemotherapy—Pemci\\m therapy rapidly elimin­ates Str pyogenes from the throat and nose, and this has two important results. It renders the patient rapidly non-infective and it lessens the risk of complications —particularly rheumatic fever. Oral therapy with phenoxymethylpemcillm is practical but" if streptococcal infection of the tonsils is to be eliminated, must be continued'for at least seven days. A single intramuscular injection of 30o>o°o to ooo ooo units of benzathine penicillin—according to age—is an effective wav of ensuring that the patient receives adequate penicillin coverage over the whole period of his illness. Unfortunately the injection is rather painful When the initial illness is severe, treatment should be started with four-hourly intra­muscular injections of benzylpenicillin ; as clinical improvement occurs treat­ment can be terminated with a single injection of benzathine penicillin, ihe important point in the administration of penicillin is that it must continue for seven days if the infection is to be adequately suppressed. When stopped too soon relapse is likely to occur. Indeed, a possible disadvantage of the use ot penicillin is its interference with the development of immunity.
Serum Treatment—The effectiveness of penicillin is such that the adminis­tration of antitoxin is now unnecessary.
Complications.—Otitis media, nephritis, arthritis, adenitis and rhinitis are complications, for the treatment of which the reader is referred to appro­priate sections of this book. Nephritis is now recognized to be associated with infection by a few special types of Str. pyogenes— particularly type 12. Ihe complication therefore tends to occur in certain epidemics only. Acute rheu­matism, on the other hand, may occur after infection by any of the serological types Penicillin therapy reduces to a minimum all of these complications which may, of course, be encountered after apparently mild infections. This is a strong argument for treating all cases with penicillin.
Convalescence.—Providing the condition of the myocardium and the pulse is satisfactory, patients with uncomplicated scarlet fever may be allowed out of bed on the seventh day of disease, and in suitable weather into the open air three days later. The treatment of the complicated case in no way differs from that advised elsewhere for the particular complication.
carriersThe mere presence of Str. pyogenes in the fauces or nose cannot be regarded as a reliable index of infectivity. Nevertheless, a rich growth of this . organism from either the throat or nose of certain persons, e.g. dairy workers, nurses, medical men, school-teachers, may reasonably be regarded as an indica­tion for continued isolation until the carrier condition has ceased. A course of systemic benzylpenicillin in doses of 0-5 mega units per day for 7 days is usually effective, but bacteriological confirmation is, of course, essential. If this fails, surgical appraisal of the condition of the nasopharynx should be advised. Antiseptic applications to the fauces and pharynx are worthless.